Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C49/00—Ketones; Ketenes; Dimeric ketenes; Ketonic chelates
  • C07C49/385—Saturated compounds containing a keto group being part of a ring
  • C07C49/395—Saturated compounds containing a keto group being part of a ring of a five-membered ring
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
  • C07C45/61—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups
  • C07C45/67—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton
  • C07C45/68—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms
  • C07C45/72—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms by reaction of compounds containing >C = O groups with the same or other compounds containing >C = O groups
  • C07C45/73—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms by reaction of compounds containing >C = O groups with the same or other compounds containing >C = O groups combined with hydrogenation

Definitions

• the present invention relates to a process for the preparation of cyclo-pentanones monoalkylated in the a-position which is significantly improved over the prior art.
• alkylation of cyclopentanone with alkyl halides in the presence of bases is also known.
• Gupta et. al cf. J. Indian Chem. Soc. 30 (1953), pages 23 to 25
• alkylation of cyclopentanone with alkyl bromides e.g. Heptyl bromide
• the 2-heptyl-cyclopentanone obtained could not be isolated as a result of numerous by-products.
• the enamine obtained was refluxed in a second stage with an aldehyde for 12 hours in benzene as solvent under reflux.
• the cooled solution was then acidified with dilute hydrochloric acid, stirred for 1 hour, extracted with benzene, the benzene extract washed with water, all of the benzene distilled off and the residue fractionated.
• the alkylidene cyclopentanones were thus obtained in a yield of 40 to 75%.
• akylidene compounds were then hydrogenated to the a-alkyl-cyclopentanones in the presence of a hydrogenation catalyst.
• the disadvantage of this process is that it consists of three sometimes very lengthy process steps and that it only gives medium yields.
• a production process with the use of amines is not very recommendable, since the alkylated cyclopentanones are largely used as fragrances and because the olfactory properties are therefore subject to the highest demands.
• Components on the one hand contain an oxide or a phosphate of magnesium, aluminum, titanium, zinc or one of the rare earth metals and on the other hand contain a noble metal from group VIII of the periodic table, preferably palladium.
• the process is particularly advantageous if the reaction is carried out under a hydrogen pressure of from 1 to about 300, preferably from 10 to about 100, in particular from 10 to 50, bar.
• the process is very advantageous if the reaction is carried out in the absence of substantial amounts of a solvent, since the space-time yields are thereby substantially improved and the workup is facilitated without loss of yield.
• the process according to the invention is generally carried out in an autoclave in such a way that all components, i.e. submit the cyclopentanone of the formula II or the corresponding cyclopentenone, the aldehyde of the formula III and the heterogeneous catalyst, close the autoclave and then flush first with nitrogen and then with hydrogen. The mixture is then heated to the reaction temperature while injecting hydrogen.
• the autoclave After the reaction is complete, the autoclave is cooled, let down and the discharge is sucked out through a filter and thus separated from the catalyst.
• the catalyst can be flushed back into the autoclave with new starting materials for the next batch using the same filters.
• the catalyst can also be left in the autoclave using an appropriately long riser pipe with a frit to discharge the liquid phase.
• the catalyst can be used several times.
• the liquid reactor discharge obtained only needs to be distilled off. If necessary, the water of reaction formed can be separated off as the lower phase before the distillation.
• the catalyst can also be used as a carrier catalyst, e.g. in the form of spheres or strands, install them firmly in a reactor column and continuously pass the mixture of cyclopentanone or pentenone and aldehyde over the catalyst under the conditions according to the invention.
• the catalyst according to the invention is, in principle, a catalyst system consisting of two components.
• the oxides or phosphates of magnesium, aluminum, titanium, zinc and one of the rare earths, such as praseodymium oxide (Pr 4 0 6 ), are suitable for this step.
• the oxides of aluminum have proven to be particularly suitable and advantageous.
• the catalyst contains a noble metal from group VIII of the periodic table, in particular palladium.
• the other precious metals - platinum, ruthenium, rhodium, iridium and osmium - are also suitable, but are generally less suitable for economic reasons.
• the catalyst can be present both in the form of a mixture of the condensation catalyst, such as A1 2 0 3 , and the hydrogenation catalyst, such as palladium on activated carbon, and in the form of a uniform catalyst, for example one containing palladium on A1 2 0 3 .
• the condensation catalyst such as A1 2 0 3
• the hydrogenation catalyst such as palladium on activated carbon
• a uniform catalyst for example one containing palladium on A1 2 0 3 .
• the only thing that is essential is the simultaneous presence of both catalyst components.
• the noble metal content is generally between 0.1 and 5% by weight. Preference is given to catalysts which contain palladium as noble metal with a content of 0.5 to 1 /, based on the amount of catalyst used.
• Suspension catalysts are used for discontinuous operation. If the reaction is carried out continuously in a reactor column, preference is given to using supported catalysts on which the noble metal, e.g. the palladium is applied. You can use the carrier material. which consists of the condensation component, impregnated with an aqueous solution containing a palladium salt such as palladium nitrate.
• the palladium metal then forms automatically under the hydrogenating conditions, but the catalyst can also be subjected to a separate hydrogenation for this purpose.
• the catalyst used in the continuous mode of operation can be used in the form of tablets, granules, spheres or extrudates; in the case of a batchwise mode of operation, the powder form is often used.
• the corresponding cyclopentenones such as 3-methyl-cyclopent-2-enone
• the double bond present also being hydrogenated under the reaction conditions, such as the double bond formed in the condensation.
• the double bond can be in any position; in this case R 2 or R 2 and R 4 or R 4 and R 6 represent the proportion of a double bond.
• the straight-chain unsubstituted aldehydes such as propanal, butanal, pentanal, hexanal, heptanal, octanal, nonanal, decanal, undecanal and dodecanal, as well as various branched and substituted ones, for example the 2-methyl-propanal, 2- Methyl-butanal, 2-methyl-pentanal, 2-methyl-hexanal, 2-methyl-heptanal, 2-methyl-octanal, 2-methyl-nonanal, 2-methyl decanal, 2-methyl-undecanal, 3-methyl- Use butanal and 3-methyl-pentanal.
• aldehydes such as propanal, butanal, pentanal, hexanal, heptanal, octanal, nonanal, decanal, undecanal and dodecanal, as well as various branched and substituted ones, for example the 2-methyl-propanal, 2- Methyl
• the molar ratio of cyclopentanone to aldehyde can be 1 to 1, but an excess of the cheaper reactant is preferably used, as a result of which the selectivity, based on the more expensive reactant, can be increased considerably.
• a solvent such as methanol, ethanol or propanol can also be used.
• the reaction temperature for the process according to the invention depends on the starting components and the type and amount of the catalyst used. It can fluctuate between 80 and 280 ° C; when using large amounts of catalyst, it can also be below 80 ° C.
• the preferred temperature range for an economical process is between 100 and 200 ° C.
• the amount of catalyst used varies depending on the reactivity of aldehyde and cyclopentanone derivative. Amounts of 3 to 8% by weight, based on the sum of the starting compounds, are preferably used.
• the hydrogen pressure can also be varied within wide limits and depends on the content of the noble metal used.
• a catalyst which is frequently used and which contains 0.5% by weight of palladium on aluminum oxide see Example 1
• hydrogen pressures between 40 and 50 bar are sufficient.
• a catalyst with a higher palladium content or when using larger amounts of the above 0.5 1 Pd / A1 2 0 3 catalyst lower hydrogen pressures are sufficient.
• unsubstituted cyclopentanones or the corresponding cyclopentenones with many aliphatic aldehydes in the ⁇ -position to the keto group can be converted in a simple one-step reaction with virtually complete conversion in high selectivity to the desired ⁇ -monoalkylated cyclopentanones.
• the process according to the invention is not only distinguished by better yields and better space / time yields, but also by its environmental friendliness, since no auxiliary bases or salts are used, but only in the presence of a heterogeneous catalyst, and therefore no saline waste water is obtained.
• a technically particularly important product of the new process according to the invention is 2-heptyl-cyclopentanone, which is an important jasmine fragrance.
• 2-heptyl-cyclopentanone which is an important jasmine fragrance.
• cyclopentanones are also suitable as fragrances (cf. Perfumer and Flavorist 8 (1983), April / May issue, pages 68 to 74).
• a mixture of 1000 ml (930 g; 11 mol) of cyclopentanone, 500 ml (425 g, 3.7 mol) of n-heptanal and 70 g of a powdery catalyst containing 0.5% by weight of palladium on aluminum oxide was placed in an autoclave. After flushing with nitrogen and hydrogen, a hydrogen pressure of 10 bar was applied at 25 ° C. and then heated to 110 ° C. for 3 hours (h) at a hydrogen pressure of 35 bar and finally at a pressure of 50 bar to 160 ° C., for which purpose about 10 hours were required. After the catalyst had been separated off, the reactor discharge was fractionated directly.
• Example 1 Analogously to Example 1, a mixture of 1008 g (12 mol) of cyclopentanone, 800 g (8 mol) of n-hexanal and 80 g of a 0.5 wt 70 bar hydrogen pressure hydrogenated to constant pressure (approx. 15 h). After the catalyst had been separated off, the reactor discharge was distilled directly. 294 g (3.5 mol) of cyclopentanone were recovered as fraction 1. The main fraction obtained 1103 g of pure 2-hexyl-cyclopentanone (bp. 84 ° C / 0.35 mbar), which corresponds to a selectivity of 82 Z based on n-hexanal. As in Example 1, the molar ratio of cyclopentanone to hexanal was increased to 3: 1. the selectivity rose to over 90% as in the case of 2-heptyl-cyclopentanone.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Catalysts (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

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• 1985
  • 1985-03-09 DE DE19853508420 patent/DE3508420A1/de not_active Withdrawn
• 1986
  • 1986-03-04 JP JP61045513A patent/JPH0627091B2/ja not_active Expired - Lifetime
  • 1986-03-06 EP EP86102996A patent/EP0194591B1/fr not_active Expired
  • 1986-03-06 DE DE8686102996T patent/DE3660590D1/de not_active Expired
  • 1986-03-07 ES ES552759A patent/ES8706104A1/es not_active Expired
• 1987
  • 1987-06-22 US US07/065,096 patent/US5081309A/en not_active Expired - Fee Related

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